Soap concentrates, for example, lithium soap concentrates, lithium complex soap concentrates, and lithium-calcium complex soap concentrates, may be utilized with a base oil, generally to thicken a base oil, to provide for a lubricating composition commonly referred to as a grease.
In addition to the individual components which make up a lubricating composition, another contributing factor to the final properties and characteristics of the lubricating composition is the particular process and conditions under which the soap concentrate and the lubricating composition are manufactured. Process conditions, for example, the dispersing and mixing of the individual components and temperature variations may be significant factors affecting the soap concentrate and the resulting lubricating composition structure, for example, the nature of the soap crystallites and fibers formed.
U.S. Pat. No. 4,392,967 to A. Gordon Alexander discloses a process for continuously manufacturing a lubricating grease using a screw process unit comprising: (a) introducing feed materials and lubricating oil into selected locations of a screw process unit which contains a series of adjacent, longitudinally connected barrel sections for performing different operative steps and houses a rotating screw device traversing the interior of the barrel sections and having separate elements along its length to perform desired operations; (b) mixing and conveying said feed materials along said process unit through the adjacent barrel sections by continuous operation of said rotating screw; (c) controlling the temperature of said material while it is being conveyed through said process unit by use of various heat exchange means which are located in or adjacent each barrel to aid in carrying out the operative steps of dispersion, reaction, dehydration and/or homogenization; (d) venting water resulting from the dehydration of the feed mixture at selected barrel discharge points in said process unit; (e) introduction of additional lubricating oil and/or additives at downstream barrel locations following the dehydration step; (f) homogenization of said complete grease formulation by continued rotation of said screw device; and (g) removal of the finished lubricating grease from the end barrel section of said screw process unit.
Despite the history of soap concentrates and lubricating compositions and processes of preparing lubricating compositions, there is still a need for a continuous process of preparing a soap concentrate as well as a resulting lubricating composition that will provide advantages regarding the process, process stability, quality control, and economy. There is also still a need to provide for a process of preparing a soap concentrate that will provide for the flexibility to be applicable for many types of lubricating compositions without significant changes in the equipment being used.
There is also still a need for a process that provides for flexibility to provide for a soap concentrate at one location that may be utilized to provide for a lubricating composition at the same location or at a different location.
There is also still a need for a process for preparing a soap concentrate, a lubricating composition, and combinations thereof that requires a low amount of water addition to minimize the energy needed to flash resulting steam.